The present invention relates to extrusion-based layered deposition systems for building three-dimensional (3D) objects. In particular, the present invention relates to extrusion heads for use in extrusion-based layered deposition systems.
An extrusion-based layered deposition system (e.g., fused deposition modeling systems developed by Stratasys, Inc., Eden Prairie, Minn.) is used to build a 3D object from a computer-aided design (CAD) model in a layer-by-layer manner by extruding a flowable build material. The build material is extruded through an extrusion tip carried by an extrusion head, and is deposited as a sequence of roads on a substrate in an x-y plane. The extruded build material fuses to previously deposited build material, and solidifies upon a drop in temperature. The position of the extrusion head relative to the substrate is then incremented along a z-axis (perpendicular to the x-y plane), and the process is then repeated to form a 3D object resembling the CAD model.
Movement of the extrusion head with respect to the substrate is performed under computer control, in accordance with build data that represents the 3D object. The build data is obtained by initially slicing the CAD model of the 3D object into multiple horizontally sliced layers. Then, for each sliced layer, the host computer generates a build path for depositing roads of build material to form the 3D object.
In fabricating 3D objects by depositing layers of build material, supporting layers or structures are typically built underneath overhanging portions or in cavities of objects under construction, which are not supported by the build material itself. A support structure may be built utilizing the same deposition techniques by which the build material is deposited. The host computer generates additional geometry acting as a support structure for the overhanging or free-space segments of the 3D object being formed. Support material is then deposited from a second nozzle pursuant to the generated geometry during the build process. The support material adheres to the build material during fabrication, and is removable from the completed 3D object when the build process is complete.
An increasing trend in the use of extrusion-based layered deposition systems involves the fabrication of large quantities of 3D objects, typically referred to as rapid manufacturing. In addition to building large quantities of identical 3D objects, rapid manufacturing may also be used to optimize a design of a 3D object by building numerous 3D objects having design variations, thereby allowing the design variations to be subsequently tested. Due to the large quantities, the components of extrusion-based layered deposition systems, particularly the extrusion heads, require good durability and reliability over extended periods of use. Thus, there is an ongoing need for improvements in the durability and reliability of extrusion heads for building 3D objects and corresponding support structures.